Automatic release mechanism



April 1950 w. L. w. OGDEN. ET AL 2,504,148

AUTOMATIC RELEASE MECHANISM 5 Sheets-Sheet 1 Filed Dec. 2, 1944 INVENTORS April 18, 1950 w. L. w. OGDEN EIAL 2,504,148

AUTOMATIC RELEASE MECHANISM Filed Dec. 2, 1944 5 Sheets-Sheet 2 O J? 55' 02 44 Z9 57 INVENTORS ATI'RNEY 5 Sheets-Sheet 3 April 18, 1950 w. L. w. OGDEN ETAL AUTOMATIC RELEASE MECHANISM Filed. Dec. 2, 1944 April 1950 w. L. w. OGDEN ETAL 2,504,148

AUTOMATIC RELEASE MECHANISM 5 Sheets-Sheet 4 Filed Dec. 2, 1944 7 Q 4/ 5 cm 3 g 3 w/ 6 O H we WU 2 o W. J M WW INVENTORS ROBE/ "7 R 65/14 577 W/LL/HM L14! 0605 A54 Fig.1

Patented Apr. 18, 1950 AUTOMATIC RELEASE MECHANISM William L. W. Ogden, Baltimore, and Robert P. Bennett, Glenarm, Md., assignors to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application December 2, 1944, Serial No. 566,362

27 Claims.

The present invention relates to automatic release mechanisms, more particularly to mechanisms for automatically opening a parachute or the like, although it is not limited to such use.

While mechanisms have been heretofore proposed for automatically opening parachutes, they have not proved successful because they either depend upon some manual manipulation for operation and hence are not fool-proof, especially when jumps are made from. high altitudes, or else they rely for operation upon a predetermined attitude of fall of the parachutist or upon the attainment of a predetermined velocity of descent or upon other factors which are insufiiciently reliable to efiect positive opening of the parachute, especially when a jump is made from an altitude sufficient to cause the parachutist to black out.

It is the primary object of this invention to provide a novel parachute opening mechanism which will automatically open the parachute when the parachutist has fallen to a predetermined altitude, or through a predetermined distance. which is positive in its action and will properly operate irrespective of the attitude of the parachutist, and is so designed that it will not interfere with normal manual operation of the parachute releasing mechanism, and which is of simple, efficient construction.

Another important object is to provide a novel release mechanism which will automatically produce a positive releasing action in response to barometric pressures of predetermined magnitude, and which is not dependent upon velocity of descent or any other factor for its operation.

A further important object of the invention is to provide an explosive type release mechanism with a novel explosive unit in which the products of the explosion are contained in a flexible, nonrupturable chamber, which undergoes expansion in response to the explosive pressures and produces the desired actuation.

Another object is to provide a release mechanism embodying a fluid pressure actuated motor having a stroke of predetermined magnitude and having a device operatively connected to said motor and operable to produce a motion having a magnitude materially greater than the stroke of the motor.

A further object is to provide a barometric switch of novel construction, embodying means for adjustably varying the pressure at which it will open or close a circuit.

Another object is to provide a parachute open- 2 ing mechanism which is fully automatic in its action and embodies a manually operable device for selectively cutting out the automatic action and placing it under fully manual control.

A further object is to provide a novel pressure responsive switch assembly in which the point at which switch actuation will occur may be variably adjusted in definite steps in terms of altitude, and yet when the transition from one altitude adjustment to another is efiected there will be no return of the mechanism to an altitude lower than either of those between which it is being adjusted.

Further objects are to provide additional improved and refined features of parachute opening mechanisms, which will become apparent as the specification proceeds in conjunction with the annexed drawings, and from theappended claims.

Figure 1 is a top plan view showing the invention applied to a parachute pack.

Figure 2 is a view of the device shown in Figure 1, as it appears when viewed from the righthand end of that view.

Figure 3 is a fragmental elevational side view of the device shown in Figures 1 and 2.

Figure 4 is a longitudinal sectional view through the explosive actuator unit of the device shown in Figure 1.

Figure 5 is a side elevational View of the unit shown in Figure 4, with the casing broken away to more clearly illustrate the structure.

Figure 6 is an end elevational view of the unit shown in Figure 5.

Figure '7 is a diametrical cross sectional view of one form of pressure actuated switch of the invention.

Figure 8 is a rear elevational view of the pressure switch of Figure 7, illustrating it as it appears when viewed from the left hand side of that figure.

Figure 9 is a front elevational view of the pressure switch of Figure 7, illustrating it as it appears when viewed from the right hand side of that figure. g

Figure 10 is an enlarged fragmental sectional view showing the manner in which the powder charge is associated with the cylinder and the hot wire detonator.

Figure 11 is a front elevational view illustrating a modified form of pressure switch also forming part of the invention.

Figure 12 is a sectional view taken substantially on the line l2-l2 of Figure 11.

Figure 13 is a sectional view taken substantially on the line l3| 3 of Figure 11, when viewed in the direction of the arrows.

Figure 14 is a top plan View, with parts broken away and in section, illustrating the spider assembly shown in Figure 12.

Figure 15 is a fragmental sectional view taken substantially along the line [-45 of Figure 11, illustrating the device for closing the contacts.

Figure 16 is a fragmental sideelevational view showing a modified form of cam assembly for use in the switch of Figures 11 to inclusive.

Figure 17 is a top plan view-of the cam'of Figure 16, the actuating screws being shown in section in the relative positions of Figure 16.

Figure 18 is an elevational view, withparts in section, of a modified form of explosive actuator unit of the invention.

Figure 19 is a longitudinal sectional view of the unit shown in Figure 18.

Figure 20 is a longitudinal sectional view,'on an enlarged scale, of the expansible' chamber -assemblyof the-device shown in Figures" 18.and 19. 1 Figure 21 is a fragmental sectional view taken substantially on the -'line 2l-2I of Figure 20,

. looking inthe direction of the arrows, and Figure 22 is an end elevation thereof.

- With continued reference to the drawings, in which like reference characters havebeen emplayed to designatesimilar parts throughout the several views, the invention .has been illustrated as being applied to a parachute pack ill,- having apair of end flaps l I .and I 2 embodying elastic cords of the .shock-cord type.l3 and M respectively, which terminate inapertured brackets '15 and I6. The latter fit over apertured pins l1 and 18, which project through. eyelets provided in a side panel!!! of canvas or the like. Pins [1 and 18 are anchored tov a side panel 20.' Panel l9 is secured to the parachute pack by means of elastic cords 2i and 22, which are fastened at their opposite ends to flap 20.

When members 15 andlli are freed from pins [1 and I8 it isapparent that flaps H, [2, l9 and 20 are releasedand the parachute will open in conventional manner. Members'l5 and 16 are releasably held in placeon members I! and I8 by means of rods or wires 23 and 24'respectively,

which pass through openings in membersl'l and I8 and, as seen'in Figure 1, are joined'together adjacent a release handle -25. The main release member 26 passesthrough an opening in the handle and has a ball-shaped abutment secured to its end, whereby movement-of the handle to the ri'ghtrin Figure 1* is operable to release both 'members'23 .and 24- from their respective pins IT and I8. A strip [2a is sewed over-fiaplZgso 'as to maintain handlein cooperative relation- 1 ship.

-We have found'that byassociating with release handle 25 a novel automatic releasermecha- .nism; which :willinow be: described, a construction is achieved in' which'zthe parachute will..be.auto- 1 .matically; and positively opened whenlzthe .parachutist has fallen to a predetermined.altitudemr through apredetermined distance -and which is ator unit '28 having a cable 29 slidably fitting in an aperture in handle 25 and provided with a "ball-shaped abutment 31' on its free endywhereby a pull upon cable 29 will move handle 25'into in any suitable manner.

. tuator .unit comprises a cylindrical tube 42 to which plates 43, M, and are secureduin any suitable manner as by means of .solder,..brazing its release position, and yet if handle 25 is manually pulled to the right, cable 29 will not interfere with such operation.

Unit 28 is secured as by means of ears 32 or the like to a mounting or foundation plate 33, which in turnis secured to the arachute pack Also secured to member 33 in any suitable manner is a pair of batteries 34, which may be ordinary dry cells, and

a pressure responsive switch 35. The actuator assembly may be enclosed by a canvas flap 36 sewed at one edge to the parachute pack and detachably fastened at its other edge to the pack by means of separable fasteners 37.

Batteries '35 are connected in series to the pressure switch by. means of a lead 38, and to the actuator unit by means of a lead 39. The pressure switch is grounded to the actuator frame or housing by means 'of a lead 4|, which completes the circuit when the switch is closed.

- Referring now :to Figures 4, 5, 6 and 10, the actotally enclose the mechanism, and it is held in place by screws and 51 threaded into flanges 5| and 52 respectively.

Passing through alined openings in plates 44 and 55, and rigidly secured therein is a tube 58 having a flaring mouth 59 and which receives a parachute operating cable 29. As seen more particularly in Figure 4, cable 29, upon emerging from tube '53 passes around a pulley 5| and thence through openings in'platesfl l and 45. Its

free end is anchored against the face of plate 54 in any suitable manner, as'by providing a knot on its encli Preferably the cable is of a metallic stranded form and has a ball-like abutment 52 rigidly secured to its end.

Pulley 5! is journaled on a pin '63 carried-by a plunger 165 which is mounted for endwise reciprocation in' tube, it being particularly observed that the tube is provided'with a slot 65 and the pulley; in projecting therethrough, keys I orrestrains-plunger 64 against rotation about its axis.

Plunger (it is provided with a piston .66

. which projects into the unslotted portion of tube 42, the latter constitutin 'the cylinder in which the actuating-fluid pressures are developed, in the manner that will now be set forth.

Referring to Figure '10, tube 42 is tightly threaded onto a threaded sleeve 6! which is'secured to or formed on-plate 45,-and threaded into the latter is a detonator bod 58 having a nut portion 69 by which it may .be-rtightly threadedinto abutting engagement :with .end portion 54 of the foundation plate. Frictionally fitting over the in- ...ner endof. memberfifiis acup. shaped receptacle H, of plastic. or other suitableeasily rupturing material, and containing apowder charge l2. The powder chargamay beexploded. in an suitable manner, but We preferably employ ahot wire 13 which is heated by the dry or other cells in response to closure of the pressure operated switch. Wire 13 is secured at one end to an insulated finger (4 carried under" the headof boltor screw 15. The. latter projects centrally through member 68 and is insulated therefrom by a non-conductive bushing I6 and an insulating washer 'II. Screw I5 is locked in place by a nut I8 and a lock washer 19.

The other end of wire I3 is carried by a finger 8I which is insulated from finger I4 by an insulating washer 82 and is clamped directly against the end of member 68, so as to make electrical contact therewith. Lead 39 may be secured to screw I5 by means of a nut 83.

From the foregoing disclosure it is apparent that heating of wire I3 in response to the passage of current will set off powder charge I2, thereby rupturing member 'II and developing a fluid pressure in tube 42 of sufiicient magnitude to drive piston 69 and connected plunger 64 and pulle GI to the left in Figure 4, where it may contact plate I 43, the latter limiting its travel. The end of cable 29 which is connected to handle 25, is as the result of the foregoing travel of piston I56, caused to be displaced a, distance twice as great as the travel of plunger 64, by reason of pulley BI and the fact that the opposite end of cable 29 is anchored to the case. It is to be understood however that the invention isnot limited to use of a pulley as a stationary guide, such as a curved trough, may be employed to revers the direction of pull of the cable, if desired.

It is accordingly apparent that handle 25 is actuated by the plunger and cable sufficiently to insure opening of the parachute, and that by employing the pulley and cable combination disclosed, it is possible to construct the explosive unit of comparatively short overall axial length, thereby making for compactness. One of the novel pressure operated switches of the invention, which may be employed to automatically complete the circuit, will now be described.

Referring now to Figures '7, 8 and 9, the pressure switch comprises a casing made up of front and rear sections 85 and 96 detachably secured together by screws 81. A snap or an other well known suitable type of switch 88, mounted in an appropriately shaped opening in casing section 86, embodies a spring-urged operating plunger 9 I, and in the position of parts illustrated is disposed in circuit-breaking position. Predetermined movement of plunger 9| to the right, under the influence of its spring, is operable to close the circuit. Plunger 9| is automatically operated in response to barometeric pressure changes by means of a bellows 92 carrying a pin 93 coacting with plunger 9I. Bellows 92 is mounted upon a spring finger 94 which is anchored to front casing section 85 at one end by a screw 95. The other end of finger 94 merel seats in a recess in casing 85, whose side walls guide it for movement toward and away from the front of the casing.

.The device may be adjusted to close switch 88 at any desired altitude by pivoting finger 94 about its anchored end, so as to adjust bellows 92 towards and away from switch 88. To this end finger 94 is provided with a projection 91 which coacts with an axially facin cam surface provided on a cam 99. The latter is journaled for rotation in a boss IOI in casing section 05, and is splined or otherwise non-rotatably secured to a dial I02 at I03. The cam has a threaded shank I04 on which a knurled nut I05 is threaded. Accordingly, when the desired pressure adjustment has been made by rotating dial I02 and cam 99, the parts may be locked in adjusted position by tightening nut I05. Dial I02 may be provided with suitable graduations I06, which cooperate with index mark I01 on the case, toachieve the proper pressure setting, a pair of ears I08 on the dial facilitating rotation thereof.

From the foregoing disclosure it is accordingly apparent that should a jump be made, at a predetermined point in the descent the increasing atmospheric pressure will compress bellows 92 and cause its pin 93 to mOVe to the right (Figure '7) and plunger 9! of switch 88 in following this movement under the influence of its spring will close the circuit, with the result that wire I3 will be heated and the powder set off, thereby automatically opening the parachute in the manner previously discussed.

In some instances it may be desirable to disarm or prevent the'device from operating until a, manual-switch is closed, especially where, in the normal use of the parachute, wide variations in altitude are frequently encountered. In Figures 11 to 15 inclusive there is disclosed a modification of the invention in which a manual switch, located in series with the pressure responsive switch, must be actuated before the device can be placed in operation. The switch shown is also of modified construction, and embodies additional advantages over the one previously described.

With continued reference to Figures 11 to 15 inclusive, a two-part casing made up of a base section I I I and a cover section H2, and secured together by screws IIII, houses the parts of the switch. A switch II3, having a spring-urged actuating plunger H4, is secured in base section I I I by screws I I5,-or in any other suitable manner. A pressure responsive bellows I I6 is carried by a bowed flexible metal strip 1, and has a boss or pin II8 cooperating with plunger II l. Strip II? is rigidly anchored at one end by a pair of screws II9 threaded into cover section H2. The other end of strip H1 is provided with a pair of slots I2I and a pair of screws I22 co operate with them to guide the free end of the strip for longitudinal movement in response to fiexure thereof under the influence of the cam setting device, which will now be described.

Mounted for rotation in a recess I24 in the upper face of the cover, and retained in place by a ring I25, having pressure graduations I26, is a setting member or knob I21. The latter is preferably provided with a detent assembly for giving the operator a definite indication when the knob is disposed in any one of its four major operative positions. The detent assembly shown comprises a plurality of balls I28 backed up by springs I 29 located in bores in the knob. The detent balls cooperate with a groove having a plurality of depressions I3I provided in the cover.

Mounted for unitary rotation with the knob assembly is a four armed spider I32, shown more clearly in Figure 14. The spider is carried by a pin I33 and is urged upwardly by a compression spring I34 located in a recess in the knob and bearing against a washer I35. The latter is carried by pin I33 and the assembly is enclosed by cap I36 secured to the. knob by screws I31. As seen more clearly in Figure 11, the upper surface of the knob is provided with an arrow formation I38, which cooperates with the graduations I25 to indicate the setting of the spider.

As seen in Figure 12, the outer end of each spider arm is provided with a notch or recess I4I which rides in a groove I42 formed inside the cover. The spider is keyed to the knob by reason of the fact that; the corner designated I43 of each arm projects upwardly beyond the outer face fIthECOVBIEMdRSGatSLiH a pocketlike recess andstapped inzthe walls'ofaeach slot is ascrew F 148. 'Screws I48are adjusted to diflerent'h'eights, ':so. as to define a he1iX',;and their =lower ends -cooperate in camming relationship with a stationary ramp or cam I49 =secured..toi:strip Hi. 1 Cam-I49 has an inclined portion and a 'flatportion, and the parts are so designed that whenthe knobisin any one .of itsxfour positions-gone of r the :screws I48 will rest 'upon the-flat portion .of :wcam ".l la'whereby 'the'ppressure at which the switch willbe actuated-may be accurately pre .35;-

- which coincides with the axis of rotationofthe with screws I658.

.-is a switch assembly'made up of apair of flexible thereto. 1

, plunger I58 before-the pressureresponsive switch I .terms ofaltitude from 5;000 to 20,000 feet, but

"'graduationsas desiredidepe'nding upon'the use' M4 provided in the knob.

From'sthe foregoing-disclosure. it is apparent of pin I33.

" Each spider arm is provided with a slot I41,

determined. When the screws I48 have been properly adjusted .theyrare lockedin adjusted ,'-;position by set screws :I5I, which pull the two 1 halves of each .arminto clamping engagement :The preferred form 1 of switch: .3 device for-renderingthe mechanism operative or inoperative atwillis constructed as follows.

- Securedtohousingv section III; byscrews I53 arms'i5 l and I55 :carrying contacts I55. Armsxgr,

. I5 and I 55 are :-provided with reversely bent portions I511adjacent the contacts, and cooperating therewith:is a plunger. I58 constructed of I insulating material'and carrying a knob 59 at its end. MemberIEBisxguided for-longitudinalga o movement in a tubeIIi-I also carried by the switch assembly and .aprojecting .outwardly through an openingtinvthe.casing. ..As seen, in Figure ll plunger. I 58 has ahandle J62 pivotly. secured c545 From-theforegoing itisapparent that in the position of the parts illustrated in .Figures .11

. and'lilplunger ifidmaintains contacts. I56 open, 1 and that theplungenis.yieldingly retained in the deviceby. reason of. reversely. curved portions-s50 I 51 engaging the. .annular groove adjacent the endof the plunger. Arms I54 and [55 are so constructedv that-when. handle. I62 is grasped and pulled, and plunger I58 removed, they will bring contacts. I56 into firm engagement. M55

The switch-assembly. is completed by an insulating block I63...which seats againstthe base.

. As seen in Figure 13, contact arm i55 is provided with an ear I64 to which the lead 4| .(of Figure ,2) is secured. Contact arm I54 is provided withmoo a side arm. Itt. which is secured tonne terminal of switch .I I3,.by .meansof a screw I61. "The other lead .38.(of Figure 2)' is secured to the other terminalofswitchJISby a'screw I69.

.It is accordingly;;apparent:thatthetwo switch devices are disposedin series and. that when leads iI and are 'connectedto the body of actuator unit 28 and to batteriesiw l'as shown in Figure 2, it is. necessary'to grasp handle I02 and remove may be operated.

Ring 25yhasbeenillustrated as graduated in it is to be; understood that it may 'carry other toiwhichthegdevice isz toebe put..::Irr-.the.formifof switch illustrated in :Figures 5.1 1;:t0 15.:inclusive,

operating knob I21 is designed to be. placed-gin one of four major operative positions,-inasmuch as cam I49-isiof insufiicient angular extenhto coactwith screwsl48 when it is disposed-between .two of them.

In some instances itmay be desirable to utilize an adjusting screw and cam assembly in which there is a progressive adjustment of the bellows,

: with noretractionbetween any of its major positions. -Whi1e1thisfeaturev is present. in the form of switch. illustrated in .Figures '7, Band 9,

we have in Figureslfi'and 11 illustrated a modifled form'of cammechanism which may be ap- :plied tothe switchof Figures.11 to115 inclusive, thereby combining :the progressive. adjustment feature with the; advantage. of providing .for Laccurate independent calibration of the instrument "ateachbf: the several major positions'of the adjustment knob.

With continued referenceto Figures 16.and T17, screws Hit are'adjustedas in the switch of Figures l1 to'l5sinclusive;-'sothat their'freeends liesubstantially in a helical path, the axis .of

assembly. A cam I'IIiissecured to strip Ill-in Y the same manner as cam I49,butin this instance it is provided with a helical face I12, which cooperates with the ends of screws l48-to'prevent the. bellows from dropping back when adjustment is made from. one pressure to another.

As seen.- in Figure 16, helical portion I12 iof the cam is approXimately'180- inangular extent and merges at its upper end into a flat portion I13 disposed normal toitsaxis- In Figures 16 and 11 the several adjusting screws have been designated M811, I481 I450 and I48d for the purpose of individually identifying them in the following description of operation.

Assuming that theparts. are in the positions illustrated in Figuresilfi and 1'1, screw I iad,

- which isshown in a position of rest on flat surface 113, determines the pressure at which the switch will operate. It should be observed that because the pitch of-helical'surface I12 is greater than the pitch of the helical path defined by the free endsof the screws; screw M is spaced from inclined face I12, whereas screw I ltahas been raised-above the plane of flat surface I13. The parts are preferably so designed that the junction between surfaces I12 and I13 is disposed approximately l5from the axis of the adjusting screws when either of them isdisposed in pressure setting position.

With the parts in the'positions just described,

if it is decidedto set the switch for a loweraltitude, knob I21 is rotated counter-clockwise (Fig- -ures 11 to 11) through .During the first-portion of the foregoing travel of knobrI21, screw I 48d merely rides over flatsurface I13 and produces no change'in the position of the bellows. However, at the endof a predetermined angular travel of knob I21, adjusting screw I480 engages and rides'up on inclined surface I12, thereby producing travel of strip II1 and the bellows'carried thereby. This also causes flat surface 113 tomove away from screw 54311. The exact point at whiehthe successive screws will strike inclinedface I12 ofthe cam will depend upon the respective pitches of thelatter and the helical path defined between ends of the screws. In any event, the pitch of surface I12 is-the :"greater, and: thereby produces the highly desirable operation justdiscusseds If the two pitches were exactly equal it is apparent that two of the screws could bear upon surface II2 simultaneously, and there would be no successive stepping up in response to counter-clockwise adjustment of knob I27. If it is desired to increase the altitude setting, knob I2'I is rotated clockwise, which causes the screws to successively ride down the inclined surface until the proper screw is brought to bear upon fiat surface I13.

From the foregoing it is apparent that the four adjusting screws may be successively adjusted from one pressure to another, without dropping back to a lower pressure in between the two points of adjustment. In other words, the'pressure setting in between any two adjacent major settings of knob I2'I will be at least as great as the lower of the two pressures, and it is also possible to secure pressure settings intermediate the four major settings illustrated by rotating knob IZ'I sufficiently to cause the screws to ride up on inclined portion I12 of the cam to various degrees.

Stop means (not shown) is provided for limiting rotation of knob I2'I to slightly less than 360, so that there is no possibility of the longest screw I48 locking behind free edge "5 of the cam.

From the foregoing disclosure it is apparent that the invention provides automatic release mechanisms which will automatically open the parachute when the parachutist has fallen to a predetermined altitude or through 'a predetermined distance, and which is positive in its action and will properly operate irrespective of the attitude of the parachutist, and is so designed that it will not interfere with the normal manual operation of the parachute releasing mechanism, and which is of simple efficient construction, and that the invention also provides novel pressure responsive switch mechanisms which, while being of particular value in the parachute releasing mechanism disclosed, are also capable of other uses, which will occur to those skilled in the art.

In Figures 18 to 21 inclusive we have illustrated a modified explosive actuator also forming part of the invention and which differs from the one previously described, primarily in that the piston and cylinder have been replaced by a flexible bellows, which retains the burning powder particles and the other products of combustion, thereby providing a device which is extremely safe and may be utilized in installations where there is danger of fire or explosion.

With continued reference to these figures, the frame assembly of this device is constructed somewhat differently than the one previously described. It embodies a base plate I8I having upturned ends I82 and I83. A cover I84 of curved form fits over end plates I82 and I83 and houses the parts. It may be secured to base I8I in any suitable manner, as for instance, by means of ears I85 and screws I86.

Secured in alined openings in end plates I82 and I83, as by welding, is a sleeve or tube I81 having a longitudinal slot I88. The explosive unit is screwed into the end of cylinder I8? as a removable and replaceable unit, in the manner to be hereinafter described.

Secured to cylinder I81 is a plate I89 and passing through alined openings therein, and in plate I83 are a pair of tubes I9I and I92. The former functions to guide actuator cable '29 around pulley I93, which is journaled on a pin I94 in plunger I95, and tube I92 guides the cable exteriorly of the unit where it is provided with an abutment I96. In this instance the plunger performs no piston functions and therefore is merely provided with a pair of guiding formations I91 and I98.

The end of cylinder I8'I is closed by plug I99, and it should be observed that with the plug in place it is impossible to move plunger I95 sulficiently to the left to permit pin I95 to be removed through either of the alined openings 28I of the cylinder. This makes it unnecessary to separately lock pin I94 in place.

The explosive unit is shown more particularly in Figures 20 and 21. It comprises a flanged member 202 which is threaded into the end of cylinder I8? and is provided with a nut portion 283 and a conical internal face 204. Threaded into member 292 is a plug member 205 having a nut portion 289 and a conical face 281.

During assembly of the device the neck 298 of a flexible bellows unit 289 is spun into place on conical seat 284, with the result that when plug 295, is threaded home, the bellows will be firmly gripped between conical faces 294 and 201, in gas-tight relationship therewith.

The powder charge is contained in a plastic cap 2 in the same manner as before, but in this instance a modified type of detonator is employed, which will now be described.

Clamped under the head of a screw 2I2, which passes centrally through plug 285 and is insulated therefrom by a bushing 2 I 3, is a washerlike member 2I4 having an upturned ear 2I5, which forms an electrode. Member 2I4 is also provided with a pair of downturned lugs 2 I5 which fit into slots 2 I "I provided in an insulating member 2I8. Mem- ;ber Elli seats against a similar washerlike element 2I9, having an electrode forming ear 22I which, as seen in Figure 21, is of sufiiciently greater length than ear 2 I 5 so that the heater Wire element 222 may be strung between them as m shown, the ends of the electrodes being bent back upon themselves to grip the wire, as shown.

Member 2I9 is provided with a pair of lugs 223 which seat in a pair of recesses 224 formed in the end of member 285.

From the foregoing it is apparent that the lug and washer assemblies maintain the several parts in proper angular relationship, and that electrode '2 I5 is insulated from plug 205 while electrode 22I is electrically grounded thereto.

Screw 2I2 is locked in place by means of an insulating washer 226, a lock washer 227 and a nut 228. Lead 39 (of Figure 2) may be electrically connected to the screw by means. of a nut 229.

This form of actuator structure of the invention functions in substantially the same way as the one previously described, except that it possesses the further highly desirable advantage of confining the products of combustion to the interior of flexible bellows 299. When the powder charge is exploded cap- 2II is ruptured and the full pressure of the explosion is transmitted to the interior of the bellows. The bellows expands and its end 23I acts directly against the end of plunger I to displace it and effect operation of the cable 29 in the manner previously set forth. It should be particularly observed that during this operation the internal walls of cylinder I81 function as an effective guide to confine the bellows to straight line expansion, thereby insuring that the full force of the explosion will be effectively utilized, inasmuch as the quantity of powder enclosed within cap '2I I is carefully calculated to produce full expansion of the bellows without effecting rupture thereof.

A further advantage is that the entire explosive i l assemblymaybe-removedas a unitfromtube I81 and-be replaced by a new unit, to again place the device in condition for operation. Also, the individual units may be reconditioned by unscrewing-p1ug- 265; and cap 2H containing the proper powder charge, and reassembling the parts.

While we-have disclosed, and prefer to employ pressure switches embodying cam devices for adjusting the pressure atwhich they will operate, because the altitude scale may be made linear by properly contouring the cam (Figure 7) or the ends of the adjusting screws (Figures 11 to 17 inclusive) it is to be understood that in the eventthat 3 scale linearity is not required, a simple screw, rigidly secured to the bellows,- and adjustablythreaded into'a nut formation on the case i I2 may be used, if desired.-

The invention may be embodied in other specific forms without departing from the spirit or essential-characteristics thereof. lhe present embodimentsare-therefore to be considered in all respects as illustrativeandnotrestrictive, the scope of the invention beingindicated by the appended claims-rather than by-the foregoing description, and'all changeswhich come within the meaning and range'of equivalencyof the claims are therefore intended to be embraced'thereby.

What is claimed, and desired to be secured by United States Letters Patentis:

1. Ida barometric circuit'controlling device, a sectional casing; a flexible fingercarried at one end by one of saidsections, a rotatable assembly journaled in saidfonecasing section and embodying means engaging said flexible finger and operable to adjustably maintain it in various degrees of-;flexur e; a pressure-responsive unit carried by saidfinger -at,a pointspaced from its point of connection to said casingsection and having an actuator..member facingtoward said other casing section; andaswitch carried .by said other casing sectionland.coactingwith .theactuator member of saidspressure. responsive unit.

2. The circuit controlling device defined in claim 1, wherein saidrotatable assembly is rotatableabout anaxis disposed substantially parallel to the axis of said pressure responsive unitand .1 embodies anaxial'ly facing camsurface which coacts with said finge12-- 3. ma parachuteopen-ing apparatus, a parachuteactuator embodying expansible f chamber.

means and a charge of powder for expanding said expansible 'chambermeans, electrically actuated s 4. Theparachute opening apparatusdefinedin claim' 3, wherein said manual switch comprises a pair of spring-fingers carrying contacts at theirfree ends,-and aninsulatingmember normally disposed'between'said members and holding said contacts-apart, said-fingers and said member having cooperating portions which'are operable to yieldinglyhold said insulating member in switch-- opening position.-

5. In a pressure responsive'switch, a casing; a

bellows unit and a switch disposed in cooperative relationship in said casing; means mounting saidbellows unit for movement toward and away from said switch, to predetermine the pressure at which said switch will operate; and means for adjusting said bellows unit, comprising a member mounted ,-"device,-' comprisingwan; outer member fOl T0tatlOlfF9vdj a'cent said'bellows' it. andhavs 1 p urality ofelez'nents projecting: toward said said bellows, and a cam provicled on said bellows 2 adjacent said elements and cooperating therewith to 'move said-bellows towardandaway from said switch in response-to rotation-of said member .in'.

one direction or the other.

6.--The pressure responsive switch definedin claim 5, wl'ieiein saidmamv means is provided? with a flat portion and la mergingvinclined por. tion; and means are provided for yicldingly hold-i;- ing: said member in suchpositicn as to cause one: of said elementsto bear. upon theflatportion of .1 said cam, whereby the apparatus may be indi-w vidually'calibratedforithel several pressures ate which it vmay be setl toi operate, by successively locating each of said. elements on said cam and: sting the element as .to cause the switch :1 to be operated: at the?particularv pressure indi-. cated by the angular position of said member;

7. in a pressure responsive switch, a casing; a bellows unit and. switch .means'mounted in-saidJ-J casing- :in :cooperative -;relationship, said bellows unit being: adapted to undergolimited movementwr toward and away from said switch, for the par-1 pose-of .predeterrniningilthe pressure at which said switchwill.cperatafmeans iortadjustingcsaid 1' bellows unit, comprisingaa member mounted for rotation in said casing; and; having an operating knob r located: exteriorly of said. casing,"a plurality of elementamcunted in said member and projecting. toward, and having: their free ends terminat i ing different. distances nom said bellows unit, and

cam means; onvsaidibellows unitcooperating in contacting engagement .with said elements, said cammeans comprisingia'flat face disposed normal to thelzaxis of rotation'of said member and includzingmeans: for preventing-"said bellows from undergoing retrogradelmovementwhen said memher is rotated zt-o cause; said elements to successively passonto and :off of said flat portion.

8. The-pressure:"switch defined in claim 7,

:wherein the endsz'of said elements define a helix and.saidclastenamed-:rneans comprises -a generally helical portionlon-said cam means merging with said-fiat portion and having a helix angle whichis greaterdhan the-angleofhelix defined Y *by thejfree ends of saidmembers. r

9. In: powderrcharge actuated mechanism, a unitary/device adapted-to be detachably secured in operativespositicniin said mechanism and to beremoved-zafter firing and, replaced'by a new having means .adaptingi-it for detachablesecurement to saidmechanism yanzinner: member carrying powderzitclia-rge means? andxz'powdercharge firing means; and :anexpans-ible bellows assembly hav-- ingr'a. closed endfittingrover said, powder charge means; said outer and 'inner members embodying means for rigidly securing the zotheri end of said bellows thereto; in: gasetightnrelationship therewith:

IDA-In a powder charge .actuatedamechanism' of l the -character :having .an 'expansible chamber" means and powder. charg'ewme'ans for expanding, said chamber means, means forxfiringsaid powder charge 'means, :comprising; 'a hollow support adapted- 50 proj ectinto said expansible'vchambepi a means a terminal projecting: through :said sup-'2 port: in insulatedrelationshipitherewitli and ha I ing means 'located-eXteriorly of saidzchambercforti making electrical connection:rtherewith; saidzterminal 'havinga-a head docated i'nteriorlyii of rsaidii-r expansible chamber; a first electrode and a second electrode and insulating means clamped between said support and the head of said terminal, whereby one of said electrodes is electrically connected to said terminal and the other electrode is electrically connected to said support; and a detonator element connected to said electrodes.

11. In a fluid motor, a base; a hollow guide secured to said base; a movable member having a portion projecting into said guide; a flexible bellows disposed within said guide and having one end thereof rigidly secured to said base and having its free end, when in collapsed condition, located in proximity to said member; a powder charge in said bellows; and means for exploding said powder charge, to cause said bellows to expand and project its free end and actuate said movable member, under the guiding influence of said guide.

12. In apparatus adapted for use with a parachute assembly including a member releasing said parachute when actuated, an expansible chamber device, a charge of material capable of producing a fluid volume greater than the volume of said charge in response to a stimulus situated within said expansible chamber device, means adapted to link an expansible portion of said chamber with said release member, electrically responsive means for applying said stimulus to said charge, a barometric pressure responsive switch, a source of electric energy, and means connecting said switch and said stimulus applying means with said source of electric energy.

13. In apparatus adapted for use with a parachute assembly including a member releasing said parachute when actuated, an expansible chamber device, a charge of material capable of producing a fluid volume greater than the volume of said charge in response to a stimulus situated within said expansible chamber device, means adapted to link an expansible portion of said chamber with said release member, electrically responsive means for applying said stimulus to said charge, a barometric pressure responsive switch presenting an open circuit in the presence of pressures less than a predetermined value, means connecting said switch and said stimulus applying means in a series circuit, and connecting leads associated with said series circuit adapted for connection to a source of electric energy.

14. In an actuating mechanism, a member mounted for reciprocation and having an end face; an actuating device mounted in cooperative relationship with said member, comprising a flexible bellows normally disposed in substantially collapsed condition with an end portion thereof in proximity to the end face of said member, means for expanding said chamber to cause said end portion thereof to engage the end face of said member propelling the latter through its range of reciprocation, comprising an explosive charge of sufficient magnitude to expand said flexible bellows and of insuflicient magnitude to effect rupture of the walls of said bellows, whereby the products of the explosion are retained in said expanded chamber, and means for detonating said explosive charge.

15. In a barometric circuit controlling device, a casing, a flexible lever having one end attached to said casing, a pressure responsive unit having an actuator element movable in response to changes in barometric pressure secured to said flexible lever at a point remote from said attached end, a switch adapted for actuation by movement of a control member carried by said casing in a position bringing said control member into engageable relation with said actuator, and

adjustable means carried by said casing engaging said flexible lever at a point remote from said attached end and movable to flex said lever.

16. In apparatus adapted for use with a parachute assembly including a member releasing said parachute when actuated, an intermediate member engageable with said release member in a unidirectional force transmitting linkage, an actuating device responsive to variations in atmospheric pressure, and a second unidirectional force linkage connecting said actuating device and said sense such that movement of said intermediate member in a predetermined sense develops a force in but one of such linkages without transmitting force to the other of said linkages.

18. In apparatus adapted for use with a parachute assembly including a tension member opening said parachute when actuated, a pressure responsive switch, a source of electric energy, electrically responsive actuating means adapted for linkage with said tension member, a manually operable switch, and means connecting said pressure responsive switch, said manually operable switch and said source of electric energy with said actuating means.

19. In an actuating unit, a body having a longitudinally slotted tube; a carrier comprising a plunger longitudinally slidable in said tube; a pulley journaled in said carrier and projecting through the slotted portion of said tube; a flexible tension element anchored at one end on said body and passing around pulley means provided on said carrier; and expansible chamber means operably connected to said carrier and operable to displace the latter in a path determined by said slotted tube.

20. In an actuating mechanism, a member mounted for reciprocation and having an end face; a walled expansible chamber in cooperative relationship with said member having an end portion disposed in proximity to the end face of said member; and means for expanding said chamber and causing the end portion thereof to engage the end face of said member and propel said member through the range of reciprocation, said expanding means comprising an explosive charge of sufficient magnitude to expand said chamber but being of insufficient magnitude to efiect rupture of the walls of said chamber, whereby the products of the explosion are retained in the expanded chamber.

21. In a fluid pressure motor, a base assembly; a plunger mounted for endwise reciprocation on said base; an expansible bellows having one end firmly anchored to said base and the other end disposed adjacent one end of said plunger; a powder charge disposed in said bellows of sumcient magnitude to cause said bellows to expand and displace said plunger through a full stroke when said powder charge is exploded, but of insufflcient magnitude to rupture said bellows when exploded; a shell-like guide surrounding said bela charge disposed in said bellows of sufiicient..mag-.,,-u

nitude to cause saidbellowstoexpand and displace said plunger througha full stroke when said powder charge 1 is exploded. but .of insufii-L cient magnitude to rupture said bellows when ex.-.--

ploded; means detachably securingsaid bellows to said base with one end of said bellows adjacent one end of said plunger, whereby said bellows may be removed as a unit subsequent to expansion and replaced by a new unit; and means for exploding said powder charge.

23. In a powder charge actuated mechanism, a unitary device adapted to be detachably' se-. cured in operative position in said mechanism and to be removed after firing and replaced by a new bellows beingesecured ztoz said memberain gas--- tight relationship therewith; I

26-.- A powder charge actuateddevice as defined by claimz wherein the the powder charge firing means comprises a pair-of 'electrodes' cara riedby'saidmember; means located exteriorlyuof said member for making electrical connection to said electrodes, and a detonator element con-- nected to said electrodes..

a unitary device adapted: to be detachably se- 27-. In a powder charge actuated mechanism,

cured-in operative'position. in 'said mechanism and .to be removed afterfiring and replaced by a new device, comprising an outer memberhaving means adapting it for *detachable securement t0---- said mechanism, an inner member carrying pow-' der' charge means and powder charge :firing means, and an expansible belloWs-assemb1y'haV-- inga closedend fitting'over" saidpowder charge ,means, the other end of said bellows being se- I cured to said innenmember in igas -tight relationship therewith.-

WILLIAM 'L.. W. OGDEN..- ROBERT P. BENNETT.

device, comprising a member carrying powder 5,-.

charge means and powder charge firing-means, and an expansible-bellows assembly having -a closed end fitting over said. powder charge means, the other end of said bellows being secured to said member in gas-tight relationship therewith.

24. In a powder charge actuated mechanism of I the character having. an expansible chamber" means and powder charge means for expanding said chamber means, comprising an expansible bellows assembly having a closed end and an open end, a support adapted to project into said open end of said expansible bellows, the said bellows being secured to said support in gas-tight relationship therewith, a pair of electrodes carried by said support, means located'exteriorly of said bellows for making electrical connectionJto said electrodes, powder charge means within said bellows, and a detonator element connected to said electrodes.

25. A powder charge actuated device comprising a member carrying powder" charge means and powder charge firing means, and an expansible bellows assembly havingfa closed'end fitting'overi. said powder charge means, the other end of said REFERENCES CITED Theiollowing references are'of-rrecord in the file of thispatent:

UNITED STATES PATENTS Number Name Date 1,229,951 Hatch June 12, 1917 1,295,471 Fleury Feb. 25, 1919 1,535,475 Jeansen Apr. 28,1925 1 1,915,435 Miller". June 27, 1933 1,985,890 Ellis Jan. 1, 1935 2,011,144 Cofiman Aug. 13, 1935 2,100,693 Irwin' Nov.'30, 1937 2,118,603 Hailey May 24, 1938 2,207,806 Hollmann 1 July 16, 1940. 2,289,318 Pratt July 7, 1942 2,299,466 Cofiman Oct. 20, 1942 2,316,009 Martin et a1. Apr. 6, 1943 2,353,440" Bresee 2 July-11, 1944 FORETGN PATENTS Number I Country Date 129,017 Great Britain July 10, 1919 278,695 (ErreatBritain Apr. 5, 1928 

